1. Field of the Invention
The present invention relates to a backup detector, and more particularly to a vehicle backup detector that indicates a distance from an obstruction.
2. Description of Related Art
Among quickly developing technologies, backup detectors for automobiles are becoming widely used to assist drivers in backing cars safely. The backup detector comprises multiple ultrasonic transducers and an alerting device. When the car is in reverse, the ultrasonic transducers in the backup detector emit ultrasonic waves. Reflected ultrasonic waves are detected by the transducers when the ultrasonic waves are reflected by an obstruction. The alerting device emits an audible warning when an obstruction is detected.
A better backup detector further comprises a video camera and a liquid crystal display (LCD). The video camera records images behind the car, and the LCD displays the images. Therefore, the alerting device and the LCD provide twice as much assistant information to the driver when the car is backing up. Furthermore, another better backup detector calculates distance between the rear of the car and the obstruction based on the travel time of a reflected ultrasonic wave between transducer emitting the ultrasonic wave and receiving the reflected ultrasonic wave. The LCD further displays a numeric distance between the rear of the car and the obstruction to provide more assistant information.
However, the backup detector is often unable to determine whether the obstruction is near the right rear or the left rear of the car. Furthermore, a long time is often required for the driver to determine the correct position of the obstruction because the driver can only see the numeric distance displayed on the LCD.
To overcome the shortcomings, the present invention provides a vehicle backup detector that indicates a distance from an obstruction to mitigate or obviate the aforementioned problems.